Switching system control



June 21,-1960 c. N. PEDERsoN swITcHING SYSTEM CONTROL Filed Nov. 19, 1956 R N O o E L M m m, .MNHN w n 1 E A om P ww ww N. L R A C M generate one hundredtwenty eight dierent codes.

, 2,942,253 'u SWITCHING SYSTEM CONTROL Y Carl N. Pederson, Westmont, Ill., assigner to Hupp Corporation, Detroit, Mich., a'corporation of Virginia Files Nov. 19, 1956, ser. No. 622,930 3 Claims. (ci. 340-4365) The present invention relates to remote switching systems which basically comprise a sender, a sender control (push-button 'key cabinet for coding thel sender) and a receiver and more particularly to improvements on the sender control unit of such systems.

General description The usual application of such systems calls for a receiver at one or more remote locations, and a sender and associated push-button sender control cabinet at one or more control locations, with all locations being interconnected by at least the equivalent of a telegraph or teletypewriter circuit. Functions at remote locations can then be performed by operating push-buttons at control locations. In the commercial embodiment of these systems, each receiver will respond to six individual code signals which are common -to'all receivers. The four common code signals normally are used for a Master Disconnect, a` Master Connect, and two Group codes. Y

With the addition of one external relay, one receiver can be made to respond to fourteen individual and four common codes, while with the addition of three external relays one receiver can be made to respond to sixty four different codes, one sender, under the control of the pushbutton sender control units, has the available capacity to The push-button control cabinets (sender control units) have v one push-button keyand a lamp for each code to be sent.

The basic sender control unit has ten such function buttons and lamps. It has, in addition, a Master Disconnect u (DISC) key for sending the code for disconnecting'any previously activated remote functions and it has a reset (RSET) key for clearing out or resetting the lamp tally. Other types are of push-button control cabinets supplement the basic model. A description and detailed explanation of these are given later.

The system employs a noncoded answer-back signal whereby any receiver which successfully performs a function, sends a short space signal to the line as an answerback. This signal, when received at the sender, lights the lamp over the push-button that was pressed to send out the signal. This lamp remains lighted until the Disconnect code is sent, and an answer-back signal to this code is received at the sender.

When the system operates on a circuit used alternately for teletypewriter signals, the average time of signalling is 2.0 seconds long and the maximum code is 2.4 seconds long. When the system operates Yon a circuit not used alternately for teletypewriter service, modifications can be made within the units so the lengths of the codefsignals can be cut approximately in half.A Each code `,signal transmitted bythe sender consists of four opensf o r space signals 'on the line.` -xTKhese are called space '.pulses, and each signal includes four 'space pulses;

. Y The interval between two space pulses von a line is ynecessarilya marking condition. `The mark intervals be- 2,942,253 Patented .lune 21, 1960 tween the space pulses of a code signal are called mark pulses. The condition of the line before the code signal starts will be marking, and the condition ofthe line' after' the code signal ends is marking. The code signal then' consists of interrupting the steady state marking condition of the line with the rst space pulse of the code signal,

followed by a mark pulse, then the second space pulse',

another mark pulse, the third space pulse, and third mark pulse, followed by the fourth space pulse and then the final steady state marking condition of the circuit.

In the basic code signal, the duration of each of the space and mark pulses is approximately sixty milliseconds.

The pulses are numbered consecutively from the be ginning of the signal. The space pulses are therefore l, 3, 5 and 7, and the mark pulses are 2, 4 and 6. Since the space pulses are always the odd numbered ones, and the mark pulses are the even numbered ones, reference to v pulses will be made by number only, there being no need for making the further statement that a pulse is a mark or a space.

For selective signalling purposes each code signal, of course, must be different from every other code signal. This difference among the signals, or the adding of intelligence to the basic signal, as it might be called, is obtained by making one or more of the pulses of each code signal a long pulse (400 milliseconds) instead of the basic short length of approximately milliseconds.

Intelligence is added to the basic code signal by lengthening both the space and mark pulses in various combinations. Since there are seven pulses which can be lengthcned, the total number of combinations possible is two to the seventh power or one hundred twenty eight. If more pulses were used, the number of combinations possible would be 512 for nine pulses, 2148 for eleven pulses and so on. i

It should be noted that the overall duration of each code signal depends upon the number of pulses in it which are long pulses, and thus the overall lengths of the various code signals will not be the same. This, of course, contrasts with the usual teletypewriter code signal where the'length of each code signal or characteris the same.-

ln the application of the system to teletypewriter circuits, pulse l is always a long pulse, for reasons concerned with the binding of teletypewriters on the circuit. This is so that the pulses of la code Vsignal do not cause printing on any teletypewriters that may be connected to the circuit during the sending of a code signal. Since this pulse is always long, there is no necessity for mentioning it in reference to the code signals.

'The basic system is one in which noI additional relays are added to a receiver to increase the number of codes to which it will respond beyond the minimum of six individual and four common codes. The codes used in the basic systems are as follows: 2, 3, 4, 5, 6, 7, 23, 24, 25, 26, 27, 34, 35, 36, 37, 45, 46, 47, 56, 57, 67, 234, 235, 236, 237, 245, 246, 247, 256 ,257, 267, 34567, 234567, and the code in which pulses 2 through 7 are short. The numbers each refer to the pulse or pulses in the code which are long pulses (400 milliseconds) compared t0 the normally short (approximately 60 milliseconds) for a pulse. Pulse lis assumed to be long in all codes.

The possibility'is remote that a code signal will be so changed in transmission that the station for which it'is intended will not respond, and that a station for which it is not intended will respond. This margin of safety results from the large differencel in the lengths of the short a close-down of the line circuit would have to occur to cause' such an effect; 'In the case f either of theseY conditions, it is probable that the same condition would obliterate one or more pulses of the code signal and no .-r'ec'eive on the line' would receivesutiicient pulses to operate any function. Therefore, anV answer-back sigrial would not be returned to the sender and repetition of the code signal wouldy be required.

For a more detailed explanation of the general systerri, reference is made to United States Patent No. 2,708,- 744, issued May 17, 1955 to I. T. Neiswinter for Selective Signalling System, and to his copeiid'ing application Serial No. 324,765, tiled December 8, 1952l for Electrica l Signalling'Systerrls'. I

As` heretofore indicated, the present invention relates pririiarily to improvements ,inY sender control units of remote switching'systens' of this type'.

lIt is` an important object of the' present invention to provide a sender control unitV embodying a plurality of selectively settable mechanically interlo'cked function selection circuit devices normally effective upon' actuation to control the transmission of a sighalindicative of the selected functionv and a function selection indicating means associated therewith to store an indicationI of each selected function, indicator resetting-means effective underl key control to release any latched function selecting key and to permit setting of the indicator to any desired indication by manipulation of the function selection keys' without transmitting any function selection signal.

A further important object of the present invention is to provide a sender control unit embodying a plurality of s'electivelysettable mechanically interlocked function selection keys normally efective'upon actuation to control the transmission of a' signal indicative of the selected function anda function selectionindicating means associated therewith to store an indication` of each selected function, means responsive to further actuation of any latched function selection key to generate a repeat transmission', of the function selection signal corresponding to the function of the latched key.

A further object of the present invention is to provide in a sender control unit embodying ay plurality of selectively settable mechanically interlocked function selection circuit devices, means for generating an impulse forl effecting initiation of transmission of av signal indicative of the' function to be selectedupon the actuation of any ofsuch circuit devices.

These and otherobjectslof the' present inv'ention'will beconiemore fully apparent by referen'cetothe'appended claims and as the following detailed description proceedsin reference to accompanying drawings wherein:

Figure 1 is a circuit diagram-of the'sender control unitof the present invention;

Figure 2is a sectional View" illustrating theA cooperationbetween a function selection key and the latch bar, with the'function selection key in its unactuated positionyand" Figure 3 is a view similar to Figure 2 illustrating the function selection key latched in its actuated position.

Referring now to the drawings'and particularly to FigureI L-the` sender control unit is`provided with twelve push-buttonkeys, keysF-Zl and F-'SG providing ten disci-'ete function selections, theVY key DISC-1 being'a disconnecty key and thel key RSET-e'l being a reset key. Ifhese keys are mechanically interlocked'by a latch bar 16. Aswitch- S-302- is mountedon the switch main frame at the' end of-the latchharso that upon depression? of anyone of theV pushdbutton keys other than RSET-l; thef" switchl S-302` is -monientarily transferred from the unactuated position shown in Figure 3Y to its actuated' position.-

The="depression of the`disconueet`-key DISC-lor of any'` on'efof the function keys F-Zl teF'-3tlis-eifective to-shftthe'latch -bar 16' to theleft as-viewedinlFigurel to momentarily transfer the contacts of switch S-302, the purposeY of which will be explained' presently. The latch bar 16 is mounted in the frame supporting the single bay switchbank formed `by the a to f contacts of these keys and is resiliently biased to the right by a compressed coil spring 18 which is compressed between a retainer 20 fixed to the latch bar y16 and portion of the frame 22. Each of the keys DISC-1, F-21 to F-SO and RSET-l is'biased outwardly by an independent compressed coil spring 24. Each ykey DISC-1 andF-Zl to F-i is formed with a metal stem 26;,(Figu're 2V) having an aperture 28 through which' the latchv bar projects and a cross bar portion 30- which',I upon depression of the key, operates upon cam surface 32 to shift the latch bar i6 to the left and which after passing the end of the cam surface 32 is received within the notch 34 in the latch bar i6 as the latch bar 16 is permitted to return to the right to retain thekeyvin,` its vdepressed position as shown in Figure 3. If a latch key is further depressed, the surface 36 on key sternA 26 will engage camsurface 32 to again shift latch bar 16;.to the left to`l shiftthe contacts of switch S-SibZ toV their transferred' position. This arrangement permits repeat transmission of a signal indicative of a selected function merely by overpressing a latched key as will become more fully apparent as the circuit description proceeds. v

In addition to movement of the latch bar by the. depression of any one of the 12 keys F-21 to F-S'tlA and DlSC-l, the latch bar may be moved in the same manner by energization of the solenoid SO-301. T he solenoid SO-Stll, as is explained in detail in copending application Serial No. 601,320, led July 31, 1956 for Remote Switching System by D. V. Sinninger, is energized upon depression of any one ofthe keys inV an expansion' unit or the reset RSET whenever any o neof theltwelve keys of the master unit of Figure l islatcheddowri. Energization of solenoid SO-Sl is effec-tiveto releaseAv the key which is latched in the unit of Figure 1. v v

The contacts c, d, e and f are wired to effect the code selection, theV contacts c and d being wired incor'nrnon'to thev pin 15 of 'FE-301 for long space:selection of the sender unit. Similarly the e' and f contacts of thel pushbutton switches connected in common through pins 8' to the sender u nit for long markselection. Thea'No., 2 contacts of movable contacts e and f of these push'- button switches are selectively wired to pins 2, 4, 6 and 17 ofTB-Stll to establish the desired codes of a long mark'in code position 2, 4, or 6 on acode of all marks long. Similarly the'No. 2 contacts' associated witlrthe movable contacts c and d of Veach of thesel switches are selectively wired to establishthe'proper, code selection to pins3`, 5, 7 andy 16 toefect theestablisliment of long spaces in' code positions 3, Sand 7' for all spaces long.

The a contacts of F-2i1 through F30 lcontrol thetransmission of the answer back signal which is yreceived from thesender unit throughk pin 9 of Tl3,-301 tothe associated one of the'an's'wer back triggers.- U The gas tube trigger double stability circuit devices in this embodiment of the invention `areeach formedlby a pair of neon lamps designated Xl andi-301 to 3io respectively. The XI lamps are preferably high pressure neon filled lamps, type NE-96, and the lamps designated I are preferably-'relatively low pressure'neon lled lamps of good visible indicating quality, type'NE-Sl. The type N13-96 tube has a iiring'potentialof V135'plusor minus 15 voltsfand -alsustainingV potential of 75 plusorminus 10 voltsa'nd is' selected forr its relatively high voltage differential between its tiring and' sustaining potentials plusor minusr 15A volts'and-a sustaining `potential ofj65 plus or minus 15voltstan'd isI selected for itsigoodcindi'- eating qualities. Due to the inherent characteristics` of this*circuit,-whentheifsetlis first turnedonor'whenpower isreslnied'afterfhaving beeiiinterripted"oriintentionaily turned off, all of the indicator lamps I-301 to I-310 will lire. A

In order that the lamps may serve as function, activ-ation record elements as well asy answer-back indications, a storage action must take place. Once a lamp is lighted it must remain lighted after the activation pulse subsides so that the pulsing source can be routed to other lamps for their subsequent activation.

The neon glow lamps exposed to view as function indicators are the I lamps, type NE-51. This type of lamp, acting alone on its differential between fire and sustain values of voltage, is not a reliable storage device. However, when paired with the high gas pressure neon glow lamp type NE-96, the combination becomes a reliable storage or bistable arrangement. This is because the N13-96 has a relatively high diierential between lire and sustain voltages even under the -widest possible tolerances encountered with respect to lamp characteristic extremes; initially and after aging. Two type NE-96 lamps operating together in a bistable or flip-op circuit make a highly reliable storage device, but this type of lamp is not as suitable for indicating service as the brighter NE- 51. Although paired NE-Sl lamps are not reliable storage elements, a circuit storage pair comprising one NE- 96 and one NE-Sl, as used in this control unit circuit, provide both adequate reliability and satisfactory illuminating properties.

Each indicator consists of a type NE-51 and a type NE-96 glow lamp connected virtually in parallel through a common resistor. Thus only one lamp of the pair can burn at a time since the sustaining voltage across the tburning lamp is below the ring voltage fof its mate. Once one of the pair is pulsed to burn, the other one extinguishes and this state endures ont-il a counter pulse reverses the order.

The arrangement of the circuit is such that the NEI-5l lamps are displayed in view over the function keys and are pulsed on individually as the remote individual functions are lactivated and return answerback pulses. Each lighting of an NE-Sl lamp extinguishes its concealed mate, the N13-96.

On a Disconnect code, theanswer-back pulse operatesv to pulse on all NIE-96 lamps simultaneously, thus extinguishing all NE-51 lamps whichl may have been burning at the moment.

The common connections between the lamps )il-301 to XI-310 to the indicator lamps I301 to I-310 respectively are connected to ground through the resistors R- 308 to R-317 `respectively which are in the commercial embodiment of the invention 150,000 ohm resistors. The opposite terminals of the lamps XI-301 to XI-310 are connected through a common line and through clamping diode CIK-301 to pin 11 of T13-301 a 150 volt D.C. connection. Pin 14 of TB-301 is connected through resistor 304 (a constant voltage `drop resistor known commercially as a Globar resistor) to the 150 volt D.C. power source at pin-11 of T13-301. The indicator lamps I-301 to I- 310 are `connected in parallel through resistors R-319 to R-SZS (100,000 ohm each) to a common line connecting them through resistor R-304 to the 150 volt D.C. power source at pin 11.

By this circuit arrangement, the voltage at the common connection betweenthe XI lamps and the I lamps with the XI lamps conducting lis plus 75 volts. This makes the voltage across the associated I lamp equal to 115 minus 75 or 40 volts so that the associated I lamp will not lire. With the I lamp conducting, the voltage at the common connection between the I lamp and the XI lamp is equal to 115 minus 65 volts or equal to 50 volts. This makes the voltages across the associated XI lamp equal to 150 minus 50 or 100 volts and the XI lamps will not fire.

The I lamps are those which form the visual indication of a received answer back signal indicative of the successful performance of the selected function. When ari answer back signal is received, it is transmitted through the No. l and 2 a contacts of the depressed one of the function keys F-21 to F-30 and is applied to the associated one of the I lamps. The receipt of an answer back signal through pin 10 is effective to apply a plus 265 volt pulsethrough the closed No. 1 and 2 a contacts of a latched one of the function selection keys F-Zl to F-30 to the associated one of the indicator lamps 1 301 to I- 310. This pulse res the one of the tubes I-30l to I-3`l0l through Which it is applied and'extinguishes the associated one of the lamps )Cl-301 to XI-310. The receipt of an answer back signal through pin l0 in response to depression of the disconnect key DISC-1 is eiective to transmit a 300 volt positive pulse through Vthe No. 1 and 2 a contacts of DISC-1 to the common line to which all of the XI tubes are connected. This tires all of the Xl tubes and extinguishes any one of the I tubes which has been iired. (The pulse voltages above given are accurate only when the respective one of the neon I and XI tubes are out ofthe circuit.)

The answer back signal received from the sender is applied through pin 10 of TB-301 to the common connection to capacitors C-303 (.25 mfd.) and C-30-4 (.1 mfd.). Capacitor C-303 is normally charged to 150 volts by a circuit from ground through R-306 (68,000 ohm), C-303 and R-SS (47,000 ohm) to the 150 volt D.C. voltage connection at pin 11. The answer back signal at pin l0 is -a connection to 150 volt D.C. voltage which is effective to raise the common connection between C-303 and R-305 to approximately 300 volts. This point is @connected to the No. 1 a contact of disconnect key DISC-1 and through pin 1 of TB-301. When the disconnect switch DISC-1 has been depressed, this pulse is transmitted through the movable a contact between contacts l and 2 to the common connectionto all of the XI tubes to lire any of those tubes which have been extinguished and thereby extinguish the tired I tubes.

The answer back signal through pin 10 of TBf-301 is also applied to the capacitor 30,4 which is normally charged to volts by the circuit from ground through R306, C-304 and R-307 (47,000 ohm). R-304 is -a non-linear resistor, known in the trade as a Globar resistor which is voltage responsive and is elective to maintain the voltage at the common connection between R-304 and R-307 at substantially plus 115 volts D.C. Resistor R-304 reduces voltage variation at the divider point to about one-iifth the value which would be present with a conventionallinear resistance type voltage divider.

The answer back signal is therefore eifective to establish a pulse of 265 volts positive at the common connection between C-304 and R-307 'which is connected to the No. 1 a contacts of each of the function selector switches F-Zl through F-Si). An answer back signal received through pin 10 of T13-301 is therefore effective to apply a 265 volt pulse signal through the No. 1 and 2 a contacts of the latched one of the function selector keys F-Zl to F-30 to the associ-ated one of the indicator lamps 1 301 to I-310 or I-40l to I-412 to render lthat lamp conductive and extinguish the associ-ated one of the XI lamps.

The depression of any one of the keys F-Zl to F-30, or the disconnect key DISC-1 is effective by shifting the latch bar 16 -to mechanically release any latched key and to momentarily transfer the contacts of the switch S-302. Capacitor C-301 (.05 mfd.) is normally charged to 150 volts through thevcircuit from ground through @-1501, R-SZ (1000 ohm), the normally closed contacts of S-SGZ to pin 11 of TB-Slll. Upon the transfer of the contacts of switch S402 upon operation of the associated latch bar, C-301 applies a pulse through the transferred contacts of S4102 to pin 12 of TB-301 which is connected to the sender unit to energize a start relay in the sender circuit. Immediately subsequently, the sender unit momentarily applies a positive signal to pin 19 of TB-301 which scagliaV is connected to theNo. 2 b contacts of disconnect switch DISC-1, andv function selector switches F-21 to 1h30.` The No. ly b* contacts of disconnect swit'chfDISC-I-and` F-21- to F-30 are- 'connected' in' common to `latch bar op er` ating solenoid SO-301; The solenoidv SO-'301- is ,CQm nected` to ground throughav` surgev capacitor C302 (204 mfd'.) and the common connection betweenY the two is connected through resistor R-303 (1000 ohm). to a movablecontact of S-302.

If, for example, key 15.4214 is latchedand'fkey-ZVZ'is prevent immediate release of a key which has justV been Y depressed. e

If however, F-Zl -is latched and any one of the function keysof 'an' expansion unit is depressed, the capacitor C-302 Awill not have been charged so thatthe positive pulse received through pin 19 will be transmitted'through the No. l and 2 b contacts of F21 to the solenoid SO-301 to energize solenoid StD-301 to operate the latch bar of the unit to release the key F-Zl. Y e

The depression of the reset key RSET-l is effective to suppress a start signal by applying ground through its No. 2 and 3 b contacts tothe pin 12 of TB301. In addition through its No, 2 and3 a contacts itapplies 150 volts D.C. from pin l1 of TB-301 to the common connectionrto the No.Y 2 b contacts of allother keys of the units to veffect release ofthe last depressed one of those keys by energization of the latch bar operating solenoids SO301. Further as the reset key RSET-l is depressed it momentarily shorts its No. l and3 c contacts together to apply momentarily 1'50 volts D.C. to the common connection between capacitors C-304 and C-iil to simulate an answer back signal which as previously described is eective if the disconnect key DISC-1 was previously depressed to lire all of the XI tubes and extinguish all of the I, tubes or if the .previously depressed key was one ofthe function selectorV keys FA-Zl to F-SQ to lire thefassociated onevof the I lamps I-301to VI-Bllil. To simulate calls the RSET-I key needs only to be pressed once andy released. Holding'it forward grounds' the Start line. When the key isin motion halfway bietween forward and back positions, a momentaryconnection is made between +150 volts and the answer back pulsing line. This simulates a pulse on that line to tire an indicator lamp I-ill to I-310 through some latched function key F-Zl 'to F430 with C-fl acting as the discharge voltagedoubli'ng capacitor. If the DISC key is latched, the pulse routes through C-SGS as the voltagedoubling capacitor. Additionally, when the RSET key is pressed to the forward position +150 volts is applied to the latch bar release lines to actuate the local solenoid through any locally pressed key or to operate the solenoid of some other expansion control unit.

From the foregoing detailed description, it is apparent that the present invention provides a greatly vimproved Sender control unit for` selective switching circuits in that it is so arranged as to be more stable in operation,4 more compact in structure and economical to manufacture, andv more rapidly adaptable to installations of widely varying function selection capacity requirements. A.

The invention may be embodied in other specific forms without departing from the spirit or essentialcharacteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. l l y What is claimed and isV desired to besecured by Unitedv States Letters Patent is: n

l. A control unit' for controlling the actuation of a transmitter for' a remote s'writcllingV system comprising'- a plurality of selectively settable vfunction selection switches, a mechanically interlocking latch mechanism so interconnecting said selection switches that upon the actuation of any one of said selection switches said one of said switches will be locked in its actuated position and during movement of said one switch to its actuated position is effective to release any previously actuated selection switch to return to its unactuated position, and meansY responsive to the movement of said latch mechanism dur'- ing the said actuation of any of said selection switches for generating a' short duration impulse for transmission to the transmitter to initiate transmission of a signal indicative-in code of the function of the actuated selection switch, said impulse generating' means comprising' a capacitor', means for ,storing a charge in said' capacitor while said latchr` mechanism is in its normal position, and means operative under control of said latch' mechanism during the' actuation of anyone of said selection switches for discharging said capacitor to thereby produce an" electrical signal.

2. The control unit defined' in claim 1 wherein said' `latch mechanism includes a spring biased latch bar and' said storing and discharging meansinclude a single' pole double throw v'switch device actuated between its two positions by moyement of said latch bar during actuating movement of any of said selection switches. Y 3. The control unit defined inclaim l wherein each of said switches when latched in' actuated position is capable of limited further movement in its direction of actuation, and said control unit further comprises means responsive to further movement of a latched switch in its actuating' direction for reactuatingv said impulse generating means to generate a further start impulse to effect retransmission of a signal indicative in code of thc' function of the' actu`4 ated selection switch.

References Eite'df in the tile of this patent UNITED STATE-s PATENTS 2,032,518l Wheelock fan Mar. s, 19136 2,558,718 Dougherty at r July 3, 1951 2,639,415 Mallery e May 19, 1953 2,720,961 smith oct. 18,1955 2,770,41)r Campbell Nov. 13-J 1956 2,836,809 MacNeill May 27, 19578 

